1. Field of the Invention
This invention relates to direct solar energy collecting, transmitting and distributing devices for illumination and heating of the interior of buildings without undesirable energy gain or loss from the building and without intermediate storage. Large flat collecting lens systems concentrate solar energy onto small light guides which traverse insulation and direct and distribute the energy to useful locations.
2. Description of the Prior Art
Windows and skylights bring the light and warmth of the sun into buildings. Even when special insulated glass is used, the energy loss from the interior is often greater than the energy required to illuminate artificially and heat gain or loss is poorly controlled by curtains.
Furthermore, much of the structural design of buildings is constrained by window placement requiring excessive exterior walls leading to greater initial cost, poor land use, and the burden of greater energy loss for the life of the building. Windows provide illumination from only one side of a room and not overhead as is usually desired. They cannot illuminate interior halls and rooms. Skylights are only useful for the top story. They provide better placement of illumination, but greater problems of heat loss and gain, preclude overhead insulation, ducts, pipes and wires and present moisture condensation problems. Known illuminating methods employing light guides or fiber optic bundles for transmitting light are well known in instrumentation such as endoscopes for observation within cavities, e.g. U.S. Pat. Nos. 4,017,150 and 3,600,568. They employ various configurations of conventional lenses adjacent a light source to focus light on a light guide and exit lenses to focus the transmitted light from the light guide onto the object being examined. The source is close to the concentrating lenses so that a substantial portion of the available light can be intercepted by a small diameter lens, and distance from first lens surface to light guide entrance is not critical. In our system, the light source, the sun, is distant and the energy is disperse. We must subtend a large area with our input lens to gather a useful amount of radiant energy. Distance from first lens surface to light guide entrance must be small relative to lens area (focal length) to allow a layer of insulation penetrated only by the light guide. Large diameter, ultra short focal length conventional lenses would be impossibly thick, heavy, and costly and would still protrude into the room from wall or ceiling, leaving no place for insulation. The present invention requires a large surface area concentrating lens arrangement with extremely short focal length that is also extremely thin so that it does not project substantially beyond the wall or roof surface where it might interfere with use of the room, placement of insulation, ducts, pipes, ceiling and the like.
Greenhouses are becoming uneconomic to operate for greater portions of the year because of increasing fuel costs to replace heat lost through glazing. Furthermore, a cost of operation has been application and removal of shading to reduce summer heat input. It is an object of the invention to provide inexpensive means to reduce heat loss in cold weather and reduce heat gain in summer.